The main objective of this study was to determine the structural load capacity of the un-injected C-pile using theoretical calculations and test loadings. The structural load capacity was studied by using Vlasov’s theory and Finite Element Method (FEM). In FEM the calculations were made by using shell elements. To find out how accurately the theoretical values of the structural load capacity correspond to reality both the continuous and extended C-piles were test loaded. The aim of test loadings was also to study the load capacity of the joint of the C-pile and how the joint affects to behavior of the extended C-pile. Another objective was to find out what is required for C-pile to get a product approval.

In the study the characteristics of the cross-section of the C-pile were determined and the equations for the structural load capacity for different load cases were presented. The study showed that calculating critical buckling loads using Vlasov’s or FEM results nearly equal result. Examination of the stability showed also that the buckling capacity of the C-pile is sensitive to the eccentricity of the compressive load. According to the load tests, the theoretical values of the structural load capacity corresponded well to the experimental. The C-pile joint welded in a way that is presented in study fulfils the standard requirements for the bending stiffness and the tensile capacity but not quite the requirement for the bending capacity. According to buckling tests the joint does not have an effect to the buckling capacity of the C-pile. Both the theoretical and the experimental studies showed that the critical buckling shape of C-pile is the flexural-torsional buckling. The buckling load of the C-pile can be calculated using Vlasov’s theory or FEM, but in both methods an extra safety factor for the eccentricity of compressive load should be used. Because the C-pile is under harmonized European standard EN 1090-1, the product approval is done by CE marking. In terms of C-pile the essen-tial requirements presented in standard EN 1090-1 and fulfilment of these require-ments are discussed.